mixin foo
  p.bar&attributes(attributes) One
  p.baz.quux&attributes(attributes) Two
  p&attributes(attributes) Three
  p.bar(class="baz")&attributes(attributes) Four
  p.baz(class=2+3)&attributes(attributes) Five

body
  +foo.hello
  +foo#world
  +foo.hello#world
  +foo.hello.world
  +foo(class="hello")
  +foo.hello(class="world")
  +foo